Various medical conditions are associated with the accumulation of glycosaminoglycans. Glycosaminoglycans (GAGs) are large complex carbohydrate molecules that participate in many biological processes. Glycosaminoglycans include polysaccharides derived from amino hexose, such as heparan, heparan sulfate (HS), hyaluronic acid, keratan sulfate, chondroitin sulfate, dermatan sulfate, and copolymers thereof. Various GAGs differ according, e.g., to the type of hexosamine, hexose, or hexuronic acid unit that they contain, as well as in the geometry of the glycosidic linkage between these units. In some instances, a GAG molecule can be broken down into disaccharide components. GAGs and GAG-derived disaccharide components can exhibit a great deal of structural heterogeneity with regards to the extent of sulfation, acetylation, epimerization, and other characteristics. On account of, in part, such variations, GAGs encompass a broad array of distinct molecules, leading to variation that contributes to challenges in quantification and characterization.
Certain GAGs, e.g., HS, are not a single compound but rather a collection of related molecules with, in some instances, different molecular weights. This is one reason that quantification or characterization of such GAGs, including HS, is not readily achievable. There is a need in the art for additional and improved methods of determining GAG levels.